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and ionizes the gas, it generates a pulse of current. The Radalert
100 electronically processes these pulses to display the radiation
level.
Alpha
Window
Cathode
(Side Wall)
Anode
Radiation Measurement Units
Several different units are used to measure radiation, exposure to
radiation, and dosage.
A
roentgen
is the amount of X-radiation or gamma radiation that
produces one electrostatic unit of charge in one cc of dry air at 0
°
C and 760 mm of mercury atmospheric pressure. The Radalert
100 displays readings in milliroentgens per hour (mR/hr). A
milliroentgen is one one-thousandth of a roentgen.
A
rad
is the unit of exposure to ionizing radiation equal to an
energy of 100 ergs per gram of irradiated material. This is
approximately equal to 1.07 roentgen.
A
rem
is the dosage received from exposure to a rad. It is the
number of rads multiplied by the quality factor of the particular
source of radiation. The rem and millirem (one one-thousandth of
a rem) are the most commonly-used measurement units of
radiation dose in the U.S. One rem is generally considered to
equal one rad.
A
sievert
is the standard international measurement of dose. One
sievert is equivalent to one hundred rems. A microsievert (
µ
Sv) is
one millionth of a sievert.
A
curie
is the amount of radioactive material that decays at the rate
of 37 billion disintegrations per second, approximately the decay
rate of one gram of radium. Microcuries (millionths of a curie) and
picocuries (trillionths of a curie) are also often used as units of
measurement.
A
bequerel
(Bq) is equivalent to one disintegration per second.